package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @description:
 * @author: panrongxiang
 * @date: 2021/7/2
 */
public class SimpleExecutor implements Executor {

    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, ClassNotFoundException, IllegalAccessException, IntrospectionException, InvocationTargetException, InstantiationException, NoSuchFieldException {
        //1.注册驱动,获取链接
        Connection connection = configuration.getDataSource().getConnection();
        //2.获取sql语句
        String sql = mappedStatement.getSql();
        //转换sql语句,转换过程中,还需要对#{}里面的值进行解析存储

        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理对象:prepareStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数
        //获取到了参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);
        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i + 1, o);
        }

        //5.执行sql
        ResultSet resultSet = preparedStatement.executeQuery();

        //6.封装返回结果集
        String resuleType = mappedStatement.getResuleType();
        Class<?> classType = getClassType(resuleType);
        ArrayList<Object> objects = new ArrayList<>();
        while (resultSet.next()) {
            Object o = classType.newInstance();
            //元数据
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {
                //字段名
                String columnName = metaData.getColumnName(i);
                //字段值
                Object value = resultSet.getObject(columnName);

                //使用反射或者内省,根据数据库表明的实体的对应关系,完成封装
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, classType);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o, value);
            }
            objects.add(o);
        }
        return (List<E>) objects;
    }

    @Override
    public int update(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws SQLException, NoSuchFieldException, ClassNotFoundException, IllegalAccessException {
        //1.注册驱动,获取链接
        Connection connection = configuration.getDataSource().getConnection();
        //2.获取sql语句
        String sql = mappedStatement.getSql();
        //转换sql语句,转换过程中,还需要对#{}里面的值进行解析存储

        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理对象:prepareStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
        String parameterType = mappedStatement.getParameterType();
        //根据首单次判定sql
        String sqlText = boundSql.getSqlText();
        int i = sqlText.indexOf(" ");
        String firstWord = sqlText.substring(0, i).toUpperCase();
        switch (firstWord) {
            case "INSERT":
                return dealWithInsert(preparedStatement, boundSql, parameterType, params);
            case "DELETE":
                return dealWithDelete(preparedStatement, boundSql, parameterType, params);
            case "UPDATE":
                return dealWithUpdate(preparedStatement, boundSql, parameterType, params);
            default:
                return -1;
        }


    }

    private int dealWithUpdate(PreparedStatement preparedStatement, BoundSql boundSql, String parameterType, Object[] params) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, SQLException {
        Class<?> parameterTypeClass = getClassType(parameterType);
        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i + 1, o);
        }
        return preparedStatement.executeUpdate();
    }

    private int dealWithDelete(PreparedStatement preparedStatement, BoundSql boundSql, String parameterType, Object[] params) throws SQLException {
        if (parameterType.contains("lang")) {
            List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
            ParameterMapping parameterMapping = parameterMappingList.get(0);
            String content = parameterMapping.getContent();
            preparedStatement.setObject(1, params[0]);
        } else {
            //id数组 批量删除
        }
        return preparedStatement.executeUpdate();

    }

    private int dealWithInsert(PreparedStatement preparedStatement, BoundSql boundSql, String parameterType, Object[] params) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, SQLException {
        Class<?> parameterTypeClass = getClassType(parameterType);
        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i + 1, o);
        }
        return preparedStatement.executeUpdate();
    }

    private Class<?> getClassType(String parameterType) throws ClassNotFoundException {
        if (parameterType != null) {
            Class<?> aClass = Class.forName(parameterType);
            return aClass;
        }
        return null;
    }

    /**
     * @description:完成对#{}的解析工作: 1.#{}使用?进行替代
     * 2.解析出#{}里面的值进行存储
     * @params:
     * @return:
     * @author: panrongxiang
     * @date: 2021/7/2
     */
    private BoundSql getBoundSql(String sql) {
        //标记处理类:配置标记计息期来完成对占位符的解析处理工作
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
        //解析出来的sql
        String parseSql = genericTokenParser.parse(sql);
        //#{}里面解析出来的变量
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();

        BoundSql boundSql = new BoundSql(parseSql, parameterMappings);
        return boundSql;
    }
}
